Head Rest Control Device and Active Head Rest

ABSTRACT

It is an object of this invention to provide an active headrest which will not over-push the head of a passenger. For this purpose, the invention provides a headrest controller for moving a part ( 20 A) or whole of a headrest ( 20 ) of a vehicle seat toward a head of the passenger to reduce the distance between the headrest ( 20 ) and the head in the horizontal direction by predicting or detecting a crash to the rear of the vehicle, including a head position detecting unit ( 11 ) for detecting a predetermined state of approach or state of contact of the headrest ( 20 ) to or with the head during the movement of the headrest ( 20 ) and a control circuit for stopping the headrest based on a detection signal from the head position detecting unit ( 11 ).

TECHNICAL FIELD

The present invention relates to a headrest controller for moving partor whole of a headrest of a seat of a vehicle toward the head of apassenger to reduce the distance between the headrest and the head inthe horizontal direction by predicting or detecting a crash to the rearof the vehicle and relates to an active headrest.

BACKGROUND ART

Various types of active headrests have been known, and known activeheadrests include, for example, those disclosed in Patent Document 1(JP-A-11-334439), Patent Document 2 (JP-A-2004-9891), Patent Document 3(JP-A-2000-309242), and Patent Document 4 (JP-A-2000-233713).

An active headrest according to an invention disclosed in PatentDocument 1 has a configuration in which the headrest is tilted based ona detection signal from a crash detecting sensor for predicting ordetecting a rear crash. It is configured such that an abutting surface(a front part) of the headrest is moved toward a passenger and is alsotilted obliquely and upwardly as the headrest is tilted.

An active headrest according to an invention disclosed in PatentDocument 2 includes a headrest driving mechanism for advancing theheadrest toward the head of a passenger when a crash to the rear of thevehicle is predicted.

An active headrest according to an invention disclosed in PatentDocument 3 includes a headrest driving mechanism for moving the headrestup and down, a sensor for detecting the position of the head of apassenger at a surface of the headrest, and elevation adjusting devicesfor adjusting the elevation of the headrest by operating the headrestdriving mechanism based on a detection signal from the sensor.

An active headrest according to an invention disclosed in PatentDocument 4 includes a headrest driving mechanism for upwardly moving theheadrest toward the head of a passenger when a crash to the rear of thevehicle is predicted.

An invention according to Patent Document 5 (JP-A-2004-122856) is avehicle passenger protection apparatus, and the passenger protectionapparatus includes prediction means for predicting a crash and movingmeans for moving a vehicle seat to a predetermined position forprotecting passenger based on a signal from the prediction means.

DISCLOSURE OF THE INVENTION Problems that the Invention is to Solved

Referring to the active headrests disclosed in Patent Documents 1 and 2,the amount of the movement of the headrests upon detection of a crash isalways constant regardless of the position of the head of a passenger.Incidentally, the position of the head of a passenger depends on thestature of the passenger and soon. As a result, the active headrestsaccording to Patent Documents 1 and 2 have sometimes been uncomfortablefor a passenger because the headrests can push the head of a passengertoo much.

Under the circumstance, it is an object of the invention to provide anactive headrest which will not over-push the head of a passenger.

MEANS FOR SOLVING THE PROBLEMS

In order to solve the above-described problem, the invention ischaracterized in that it provides a headrest controller and an activeheadrest having a configuration as described in each claim.

A headrest controller according to a first invention includes a headposition detecting unit for detecting a predetermined state of approachor state of contact of a headrest to or with a head during the movementof said headrest and a control circuit for stopping the headrest basedon a detection signal from said head position detecting unit.

Therefore, the headrest can be stopped at a proper position inaccordance with the position of the head of a passenger. For example,the headrest can be stopped at a position where the head will not beover-pushed.

In a headrest controller according to a second invention, the headposition detecting unit includes two or more sensors which are differentfrom each other in the method of detection. The control circuit stopsthe headrest when the predetermined state of approach or state ofcontact is detected by any of the sensors.

In a headrest controller according to a third invention, the headposition detecting unit includes a sensor for detecting thepredetermined state of approach and a sensor for detecting the state ofcontact. The control circuit stops the headrest when the predeterminedstate of approach or state of contact is detected by either of thesensors.

In a headrest controller according to a fourth invention, the headposition detecting unit has a plurality sensors of at least one type ofsensor among the two or more types of sensor different from each otherin the method of detection.

In a headrest controller according to a fifth invention, the headposition detecting unit has a plurality sensors of at least one type ofsensor among a type of sensor for detecting the predetermined state ofapproach or a type of sensor for detecting the state of contact.

Headrest controllers according to sixth and seventh inventions have aconfiguration in which the head position detecting unit is provided in afront part of the headrest.

A headrest controller according to an eighth invention includes a crashdetecting sensor for predicting or detecting a crash to the rear of thevehicle, a headrest driving mechanism for moving part or whole of aheadrest of a vehicle seat toward a head of a passenger to reduce thedistance between the headrest and the head in the horizontal direction,a head position detecting unit for detecting that the headrest hasentered a predetermined state of approach or state of contact to or withthe head, and a control circuit for operating the headrest drivingmechanism when the crash detecting sensor outputs a detection signal andstopping the headrest driving mechanism when the head position detectingunit outputs a detection signal.

It is therefore possible to move the headrest toward the head of thepassenger and to stop the headrest at a proper position in accordancewith the position of the head of the passenger.

In a headrest controller according to a ninth invention, the headposition detecting unit includes sensors of two or more types of sensorwhich are different from each other in the method of detection. Thecontrol circuit stops the headrest when the predetermined state ofapproach or state of contact is detected by any of the sensors.

In a headrest controller according to a tenth invention, the headposition detecting unit includes a sensor for detecting thepredetermined state of approach and a sensor for detecting the state ofcontact. The control circuit stops the headrest when the predeterminedstate of approach or state of contact is detected by either of thesensors.

In a headrest controller according to an eleventh invention, the crashdetection sensor is a sensor for predicting a crash to the rear of thevehicle, and the control circuit is configured to return the headrest toan initial position by operating the headrest driving mechanism in theopposite direction when a predetermined time passes after the crashdetecting sensor outputs a detection signal.

Therefore, according to the invention, the headrest returns to theinitial position when the predetermined time passes after it is moved.Thus, the headrest is automatically returned to the initial positionwhen the forward movement becomes unnecessary, e.g., when no crash hasoccurred. Since the headrest is thus returned to its normal state, it iseasy to use.

An active headrest according to a twelfth invention includes a headrestdriving mechanism for moving a front part of a headrest in a front-reardirection in which the distance between the head of a passenger and thefront part of the headrest is decreased, a head position detecting unitfor detecting the distance between the head of the passenger and thefront part of the headrest in the front-rear direction, and adjustingdevices for adjusting the distance between the head of the passenger andthe front part of the headrest in the front-rear direction to apredetermined amount distance by stopping the headrest driving mechanismbased on a detection signal from the head position detecting unit.

It is therefore possible to move the front part of the headrest towardthe head of the passenger and to stop the front part of the headrest ata proper position in accordance with the position of the head of thepassenger. For example, the front part of the headrest can be stopped ata position where the head will not be over-pushed by the front part ofthe headrest.

An active headrest according to a thirteenth invention includesautomatic retraction devices which moves the front part of the headrestrearward when the front part of the headrest has been stopped for apredetermined time at a predetermined position in which the distancebetween the head of the passenger and the front part of the headrest isthe predetermined amount.

That is, the front part of the headrest returns to the initial positionwhen it has spent the predetermined time in the predetermined position.

Therefore, the front part of the headrest is automatically returned tothe initial position when the forward movement becomes unnecessary,e.g., when no crash has occurred. Since the headrest is thus returned toits normal state, it is easy to use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rear perspective view of an active headrest according toEmbodiment 1;

FIG. 2 is a rear perspective view of the active headrest according toEmbodiment 1;

FIG. 3 is a partial transverse sectional view taken along the line A-Ain FIG. 1;

FIG. 4 is a vertical sectional view taken along the line B-B in FIG. 2;

FIG. 5 is a front perspective view of the active headrest according toEmbodiment 1;

FIG. 6 is a vertical sectional view of a contact detecting sensoraccording to Embodiment 1;

FIG. 7 is a vertical sectional view of the contact detecting sensoraccording to Embodiment 1;

FIG. 8 shows components constituting a headrest controller according toEmbodiment 1;

FIG. 9 shows components constituting a headrest controller according toEmbodiment 2; and

FIG. 10 is a flow chart of a control method of the headrest controlleraccording to Embodiment 2;

DESCRIPTION OF REFERENCE NUMERALS

-   -   1: active headrest    -   2, 7: contact detecting sensor    -   5: control circuit    -   6: approach detecting sensor    -   11, 13: head position detecting unit    -   12: timer    -   20: headrest    -   20A: front part    -   20B: rear part    -   30: headrest driving mechanism    -   33, 34: guide hole    -   35, 36: link member

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

Embodiment 1 will now be described according to FIGS. 1 to 8.

As shown in FIG. 1, an active headrest 1 includes a headrest 20 and apair of legs 38 protruding downward from a bottom surface of theheadrest 20.

The legs 38 are connected to a frame (omitted in the figure) provided ona seatback 10 such that it can be moved up and down, whereby theheadrest 20 is supported above the seatback 10 such that it can be movedup and down.

As shown in FIG. 4, the headrest 20 is divided into a front part 20Aconstituting a front part thereof and a rear part 20B constituting arear part thereof. A headrest driving mechanism 30 is provided betweenthe front part 20A and the rear part 20B, and a head position detectingunit 11 having a plurality of contact detecting sensors 2 is provided inthe front part 20A.

The front part 20A and the rear part 20B have plates 21 and 22 made ofresin on the sides of the division as shown in FIG. 4, and pads 23 and24 molded from urethane foam or the like in positions outside of theplates 21 and 22. The surface of the pads 23 and 24 is covered by skins25 and 26 made of leather or cloth.

The plate 22 of the rear part 20B is attached to the legs 38 through abase 32. Therefore, the rear part 20B is supported on the seatback 10through the legs 38.

The front part 20A is connected with the rear part 20B through theheadrest driving mechanism 30. As a result, the front part 20A is movedby the headrest driving mechanism 30 between an initial position that isshown in FIG. 1 and an operating position that is shown in FIG. 2.

As shown in FIG. 3, the plates 21 and 22 have shielding side portions 21a and 22 a which are integral therewith, and the side portionsprotruding from a right end and a left end toward the other plates 21and 22 as shown in FIG. 3.

The shielding side portions 21 a and 22 a overlap each other such thatthe shielding side position 21 a is located inside the shielding sideportion 22 a. The shielding side portions 21 a and 22 a are in anoverlapping relationship even when the front part 20 a is moved forwardto the operating position as shown in FIG. 4.

A shielding sheet 28 constituted by a resin film is stretched betweenthe front part 20A and the rear part 20B as shown in FIG. 2.

As shown in FIG. 4, a frontward end of the shielding sheet 28 isattached to an upper edge of the plate 21, and a rearward end of thesame is attached to an upper edge of the plate 22. Both of left andright ends of the shielding sheet 28 extend along the shielding portions21 a and 22 a in a free state.

Therefore, the shielding sheet 28 is spread between the front part 20Aand the rear part 20B when the front part 20A is in the operatingposition shown in FIG. 2 to cover the top side of a gap formed betweenthose parts. When the front part 20A is put in the initial positionshown in FIG. 1, the sheet is folded into the gap between the front part20A and the rear part 20B.

As shown in FIG. 4, the headrest driving mechanism 30 has link members35 and 36, bases 31 and 32, and an electric drive unit (omitted in FIG.4).

The bases 31 and 32 are attached to inner surfaces of the plates 21 and22 as shown in FIG. 3. Upright portions 31 a and 32 a are formed atright and left edges of the bases 31 and 32 so as to stand from theplates 21 and 22. The upright portions 31 a and 32 a are formed withguide holes 33 and 34 as shown in FIG. 4.

The guide hole 33 is a slot which is located in an upper region of theupright portion 31 a and elongated in the vertical direction. An upperend of the link member 36 is supported at the guide hole 33 through apin 36 a such that it can be moved up and down.

The guide hole 34 is a slot which is located in a lower region of theupright portion 32 a and which is elongated in the vertical direction. Alower end of the link member 36 is supported at the guide hole 34through a pin 36 b such that it can be moved up and down.

As shown in FIG. 4, the link members 35 and 36 are rotatably connectedby a pin 37 at intermediate portions thereof to form an X-linkmechanism.

The link members 35 and 36 are mounted to the front part 20A at one endthereof and mounted to the rear part 20B at another end thereof. Thatis, an upper end of the link member 35 is rotatably mounted to an upperregion of the upright portion 32 a through a pin 35 a. A lower end ofthe same is rotatably mounted to a lower region of the upright portion31 a through a pin 35 b. The upper end of the link member 36 issupported at the upper region of the upright portion 31 a such that itcan be moved up and down, and the lower end of the same is supported ata lower region of the upright portion 30 a such that it can be moved upand down.

The electric drive unit is a feature to operate the X-link mechanismconstituted by the link members 35 and 36, and it includes, for example,a motor. For example, the electric drive unit is assembled to the base32 and located between the front part 20A and the rear part 20B. Theelectric driven unit is configured such that it moves the pin 36 b upand down along the guide hole 34 to move the lower end of the linkmember 36 up and down and to thereby operate the link members 35 and 36like a pantograph.

Thus, the headrest driving mechanism 30 moves the front part 20A in thedirection of making it closer or further to or from the rear part 20B.

The active headrest 1 has over-push prevention device (adjustingdevices) and automatic retraction device.

The over-push prevention device is for adjusting the amount of movementof the front part 20A in accordance with the position of a head of apassenger to prevent the head of the passenger to be pushed too much bythe front part 20A when moved.

The over-push prevention device includes a control circuit 5 forcontrolling the headrest driving mechanism 30 and a head positiondetecting unit 11 having a plurality of contact detecting sensors 2 (seeFIGS. 5 and 8).

The head position detecting unit 11 is provided in the front part 20Aand moved toward the head of a passenger along with the front part 20A.

The contact detecting sensors 2 are configured to generate a signal whenthe front part 20A abuts on the head of a passenger, so that they detectan abutting position in which the front part 20A abuts on the head ofthe passenger.

For example, the contact detecting sensors are planar touch sensors asshown in FIG. 6 which include two disc-shaped plates 2 a and 2 b and aspacer 2 c provided between the two plates 2 a and 2 b. A lead wire 3 isconnected to each of the two plates 2 a and 2 b. The sensors areconfigured such that the plate 2 a is deformed toward the plate 2 b asshown in FIG. 7 when a force F acts on the plate 2 a to put the plate 2a and the plate 2 b in contact with each other.

The contact detecting sensors 2 are provided inside a front surface ofthe front part 20A as shown in FIG. 4, and they are provided, forexample, between the skin 25 and the pad 23. The plurality of contactdetecting sensors 2 are provided in a wide range of a front region ofthe front part 20A in a dispersed manner.

The plurality of contact detecting sensors 2 are electrically connectedthrough the lead wires 3. Therefore, a detection signal from theplurality of contact detecting sensors 2 can be transmitted to thecontrol circuit 5 using a small number of signal lines.

As shown in FIG. 8, the control circuit 5 receives a detection signalfrom the contact detecting sensors 2 and controls the headrest drivingmechanism 30 based on the detection signal. Thus, the front part 20A isstopped at the abutting position.

Therefore, the stopping position (the amount of movement) of the frontpart 20A depends on the position of the head of the passenger.

The automatic retraction device is for automatically retracting thefront part 20A to the initial position the front part had assumed beforethe movement, the retracting beginning when the stop time spent by thefront part 20A at the abutting position reaches a predetermined time.The automatic retraction device includes a timer 12 and the controlcircuit 5 (see FIG. 8).

The timer 12 measures the stop time that the front part 20A spends atthe abutting position. When the stop time reaches the predeterminedtime, e.g., 1 to 15 seconds, the control circuit 5 operates the headrestdriving mechanism 30 in the opposite direction to retract the front part20A to the initial position.

The retracting speed of the front part 20A is preferably lower than theadvancing speed of the front part 20A.

The vehicle is also provided with a crash detecting sensor 4 forpredicting a crash to the rear of the same, and the crash detectingsensor 4 is configured to generate a signal when it predicts a crash tothe rear.

As shown in FIG. 8, the headrest controller has the crash detectingsensor 4, the head position detecting unit 11, the control circuit 5,the timer 12, and the headrest driving mechanism 30. A method of controlexercised by the headrest controller on the active headrest 1 will nowbe described.

When the crash detecting sensor 4 predicts a crash to the rear andgenerates a detection signal, the control circuit 5 operates theheadrest driving mechanism 30 based on the detection signal. Then, thelink members 35 and 36 operate to move the front part 20A away from therear part 20B as shown in FIG. 4, and the front part 20A is movedforward and upward from the initial position toward the head of thepassenger.

When the front part 20A abuts on the head of the passenger, the contactdetecting sensors 2 detects it and output a detection signal. Thecontrol circuit 5 stops the headrest driving mechanism 30 based on thedetection signal. Thus, the front part 20A is stopped at the abuttingposition.

Thus, the front part 20A protects the passenger from shock at the timeof the possible or predicted crash to the rear of the vehicle.

When no crash to the rear of the vehicle occurs, the automaticretraction device automatically retracts the front part 20A to theinitial position which the front part had assumed prior to the movementand after a predetermined time has passed.

The active headrest 1 is configured as described above.

Specifically, the headrest controller includes the head positiondetecting unit 11 for detecting the state of contact of the headrestwith the head during the movement of the headrest (20A) and the controlcircuit 5 for stopping the headrest (20A) based on a detection signalfrom the head position detecting unit 11 (see FIG. 8).

Therefore, the headrest (20A) can be stopped at a proper position inaccordance with the position of the head of the passenger. The headrestcan be stopped at a position where the head is not over-pushed by theheadrest.

The active headrest 1 includes the automatic retraction device whichmoves the front part 20A of the headrest 20 rearward when the front part20A of the headrest 20 has been stopped for a predetermined time in apredetermined position in which the distance between the head of apassenger and the front surface of the headrest is a predeterminedamount.

Therefore, when the forward movement has been unnecessary, e.g., when nocrash to the rear has occurred, the front part 20A is automaticallyreturned to the initial position. Since the headrest 20 is thus returnedto its original position, it is easy to use.

Embodiment 2

Embodiment 2 is configured similarly to Embodiment 1. However,Embodiment 2 includes a head position detecting unit 13 as shown in FIG.9 instead of the head position detecting unit 11 shown in FIG. 8.Embodiment 2 will be described below, the description focusing ondifferences from Embodiment 1.

The head position detecting unit 13 includes two or more sensors whichare different from each other in the method of detection. For example,the head position detecting unit 13 includes approach detecting sensors6 and contact detecting sensors 7.

The approach detecting sensors 6 are for detecting a state of approachbetween a headrest and a head of a passenger. For example, they aresensors which output detection signals when the distance between theheadrest and the head of a passenger becomes 20 mm or less or, morepreferably, 10 mm or less.

For example, the approach detecting sensors 6 are capacitance typesensors which include two capacitor plates, which are configured toutilize the head of a passenger as a dielectric body between the twocapacitor plates.

The contact detecting sensors 7 are sensors for detecting a state ofcontact between the front part of the headrest and the head of thepassenger. For example, they have the same configuration as the contactdetecting sensors 2 shown in FIGS. 6 and 7.

The approach detecting sensors 6 and the contact detecting sensors 7 maybe formed as separate bodies, and each of them may alternatively beintegrally formed as a hybrid type.

The head position detecting unit 13 has a plurality of sensors of atleast one type among two or more sensors employing different methods ofdetection. For example, the unit includes a plurality of either or bothof approach detecting sensors 6 and contact detecting sensors 7.

Those sensors are provided in a front region of the headrest in adispersed manner. The plurality of sensors are electrically connected toeach other with lead wires and are connected to a control circuit 5. Forexample, a plurality of the approach detecting sensors 6 are connectedto each other with lead wires and are connected to the control circuit5. A plurality of the contact detecting sensors 7 are connected to eachother with lead wires and are connected to the control circuit 5.

As shown in FIG. 9, the headrest controller includes the crash detectingsensor 4, approach detecting sensors 6, contact detecting sensors 7,control circuit 5, timer 12 and headrest driving mechanism 30.

A method of control exercised on the headrest controller (headrest) bythe control circuit 5 will now be described according to FIG. 10.

First, the control circuit 5 determines whether a first routine hasended or not from a value F1 (step S1). If it is determined that thefirst routine has ended (if F1=1), it is determined whether a secondroutine has ended or not (step S7).

If the first routine has not ended (if F1=1 is not true) a detectionsignal is fetched from the crash detecting sensors 4 (step S2). It isthen determined whether there is a possibility of a crash to the rear ofthe vehicle based on the detection signal (step S3).

If it is determined that no crash to the rear of the vehicle will occur,the control routine is terminated. If it is determined that a crash tothe rear of the vehicle will occur, F1 is set at 1 (step S4). Then, thetimer 12 is started (step S5), and the headrest driving mechanism 30 isoperated.

Thus, the front part of the headrest is advanced toward the head of thepassenger.

Subsequently, it is determined whether the second routine has ended ornot from a value F2 (step S7). If it is determined that the secondroutine has ended (if F2=1), it is determined whether the time measuredby the timer 12 has exceeded a predetermined time or not (step S13).

If it is determined that the second routine has not ended (if F2=1 isnot true), a detection signal from the approach detecting sensors 6 anda detection signal from the contact detecting sensors 7 are fetched(step S8).

Next, it is determined whether there is a state of approach in which thedistance between the headrest and the head of the passenger is equal toor smaller than a predetermined amount based on the detection signalfrom the approach detecting sensors 6 (step S9).

When it is determined that there is a state of approach, F2 is set at 1(step S11).

When it is determined that there is no state of approach, it isdetermined whether the headrest is in contact with the head of thepassenger based on the detection signal from the contact detectingsensors 7 (step S10). The control routine is terminated when it isdetermined that there is no state of contact.

When it is determined that there is a state of contact, F2 is set at 1(step S11). The headrest driving mechanism 30 is then stopped (stepS12). As a result, the headrest is prevented from over-pushing the headof the passenger in the forward direction.

Next, it is determined whether the time measured by the timer 12 hasexceeded the predetermined time (step S13). If the measured time has notexceeded the predetermined time, the control routine is once terminatedand then resumed.

When the measured time has exceeded the predetermined time, the headrestdriving mechanism 30 is operated in the opposite direction (step S14).Thus, the front part of the headrest is returned to the initialposition. Consequently, the front part of the headrest returns to theinitial position after stopping at the predetermined position for thepredetermined time. Finally, F1 and F2 are set at 0 (step S15).

Embodiment 2 is configured as described above.

Specifically, the head position detecting unit 13 includes two or moresensors which are different from each other in the method of detection.For example, it includes the approach detecting sensors 6 for detectinga predetermined state of approach and the contact detecting sensors 7for detecting a predetermined state of contact. The control circuit 5stops the headrest when the predetermined state of approach or the stateof contact is detected by either of the sensors.

Therefore, a state in which the headrest is approaching the head of thepassenger or in contact with the same is detected by either of thesensors. Even when the state is not detected either of the sensors, thestate can be detected by another sensor. The state of approach or thestate of contact can therefore be reliably detected.

Embodiment 3

Embodiment 3 is configured substantially the same as Embodiment 1.However, Embodiment 3 includes a camera mounted on the ceiling of acabin and a head position detecting unit having a measuring device formeasuring the distance between the head of a passenger and a headrestbased on a picture from the camera instead of the head positiondetecting unit 11 shown in FIG. 8.

The embodiment has a configuration in which a control circuit stops theheadrest based on a signal from the head position detecting unit.

Other Embodiments

The invention is not limited to Embodiments 1 to 3 and may beimplemented in the following modes.

(1) The active headrests according to Embodiments 1 to 3 are configuredto operate based on a detection signal from a crash detecting sensor forpredicting a rear crash. Alternatively, an active headrest may include acrash detecting sensor for detecting a rear crash and may be configuredto operate based on a signal from the crash detecting sensor.

(2) The head position detecting unit according to Embodiment 1 includescontact detecting sensors for detecting that a front part of a headresthas abutted on the head of the passenger. Alternatively, the headposition detecting unit may have a configuration including approachdetecting sensors according to Embodiment 2 instead of the contactdetecting sensors.

(3) The head position detecting units according to Embodiment 1 and 2are provided between a skin and pads as shown in FIG. 4. Alternatively,a configuration may be employed, in which the head position detectingunit is provided within the thickness of the skin. For example, aconfiguration may be employed, in which the skin has a leather layer anda laminate layer and in which the head position detecting unit isprovided between the leather layer and the laminate layer. The headposition detecting unit may alternatively be provided in a pad.

(4) The headrests according to Embodiments 1 to 3 have a dividedconfiguration including a front part and a rear part. Alternatively, anintegral configuration may be employed, in which a headrest includes afront part and a rear part integral with each other similar to those inthe headrest according to Patent Document 1 and in which the front partof the headrest is tilted (moved) along with the headrest as a whole.

(5) The head position detecting units according to Embodiments 1 and 2include a plurality of sensors, and the plurality of sensors areprovided in a front part of a headrest in a dispersed manner.Alternatively, a configuration may be employed, in which one or aplurality of sensors occupy a wide area of the front side of the frontpart, e.g., 80% or more of the front region.

(6) The automatic retraction devices according to Embodiments 1 to 3retracts a front part of a headrest after the front part of the headrestis kept stopped for a predetermined time at a predetermined position.Alternatively, a configuration may be employed, in which the automaticretraction devices includes determination means for determining that nocrash to the rear of a vehicle will occur, e.g., determination means fordetermining that the object of measurement has become further and inwhich the front part of the headrest is retracted based on a signaloutput by the determination means.

(7) The invention may be configured as follows.

(Claim A)

“An active headrest, a front part of the headrest being moved along withthe headrest as a whole or away from a rear part of the headrest towardthe head of a passenger based on a signal from a sensor for predictingor detecting a crash to the rear of the vehicle, characterized byincluding over-push prevention devices for adjusting the amount ofmovement of the front part of said headrest according to the position ofthe head of said passenger to prevent the front part of said headrestthus moved from over-pushing the head of said passenger”

Therefore, according to the invention, the front part of the headrestmoves toward the head of a passenger and stops at a proper position inaccordance with the position of the head of the passenger. That is, thefront part stops at a position in which the head is not over-pushed.Thus, the head of the passenger is prevented from being over-pushed bythe front part of the headrest.

(Claim B)

“An active headrest as in claim A, characterized in that the over-pushprevention devices is configured to stop said front part in an abuttingposition in which the front part of the headrest abuts on the head ofthe passenger or in a near position in which the distance of said frontpart to the head of said passenger is equal to or smaller than apredetermined value.”

Therefore, according to the invention, the front part of the headrestmoves toward the head of a passenger and stops at the abutting positionor the near position. As a result, it is possible to prevent the frontpart of the headrest from over-pushing the head of the passenger and toprotect the passenger properly at the time of a rear crash or before arear crash.

(Claim C)

“An active headrest as in claim B, characterized in that the over-pushprevention device includes a head position detecting unit for detectingthat the front part of the headrest has abutted on the head of thepassenger or has approached to the same up to the near position and isconfigured to stop the front part of said headrest based on a detectionsignal from the head position detecting unit”.

Thus, according to the invention, the over-push prevention deviceincludes a head position detecting unit. The head position detectingunit detects an abutting position or a near position (hereinafterreferred to as an abutting position or the like) when the front part ofthe headrest is moved. As a result, the over-push prevention device caneasily detect the abutting position or the like because it has the headposition detecting unit. Since the head position detecting unit detectsthe abutting position or the like when the front part is moved, theabutting position or the like in accordance with the position of thehead of the passenger. Thus, the abutting position or the like is easilyand accurately detected, which makes it possible to stop the front partof the headrest at a proper position easily.

(Claim D)

“An active headrest as in claim C, characterized in that the headposition detecting unit is provided in the front part of the headrest.”

Therefore, according to the invention, the head position detecting unitcan detect the abutting position or the near position in a positionclose to the head. As a result the head position detecting unit canaccurately detect the abutting position or the near position.

(Claim E)

“An active headrest as in claim D, characterized in that the headposition detecting unit includes a plurality of sensors and that theplurality of sensors are provided in a front region of the front part ofthe headrest in a dispersed manner.”

Therefore, according to the invention, the head position detecting unitcan detect the abutting position or the near position in a wide range ofthe front side of the front part. As a result, the head positiondetecting unit is configured such that it can properly work in aposition in the lateral direction of the head of the passenger.

(Claim F)

“An active headrest according to any of Claims A to E, characterized byincluding automatic retraction devices which automatically retracts saidfront part to the initial position that the front part assumed beforethe movement when the stop time of the front part of the headrest at theabutting position or the stop time of the same in the near positionreaches a predetermined time or when a predetermined signal isreceived.”

Therefore, according to the invention, the front part of the headrestreturns to the initial position when the predetermined time passes afterit is moved. As a result, the front part is automatically returned tothe initial position when the forward movement has become unnecessary,e.g., when no rear crash has occurred. Since the headrest thus returnsto the normal state, it is easy to use.

1-13. (canceled)
 14. A headrest controller for moving a headrest of avehicle seat toward a head of a passenger comprising: a headrest and anobject positioned adjacent the headrest; a head position detecting unitincluding a first sensor to detect a distance between the object and theheadrest, and a second sensor for detecting contact between the objectand the headrest; and a control circuit to alter movement of theheadrest based on a detection signal from the head position detectionunit.
 15. A headrest controller as in claim 14, wherein the first sensoris a plurality of sensors.
 16. A headrest controller as in claim 14,wherein the first sensor is a capacitive type sensor.
 17. A headrestcontroller as in claim 14, wherein the second sensor is a plurality ofsensors.
 18. A headrest controller as in claim 14, wherein the secondsensor is a contact type sensor.
 19. A headrest controller as in claim14, wherein the head position detecting unit is provided in the frontpart of the headrest.
 20. A headrest controller comprising: a crashdetecting sensor for predicting or detecting a crash to a rear of avehicle; a headrest driving mechanism for moving part or whole of aheadrest toward a head of a passenger to reduce the distance between theheadrest and the head; a head position detecting unit including a firstsensor to detect a distance between the head and the headrest, and asecond sensor for detecting contact between the head and the headrest; acontrol circuit for operating the headrest driving mechanism when thecrash detecting sensor outputs a detection signal and altering movementof the headrest driving mechanism when the had position detecting unitoutputs a detection signal, further wherein the control circuit alter,wherein the control circuit stops the headrest when the predeterminedstate of approach or state of contact is detected by either of thesensors.
 21. A headrest controller as in claim 20, wherein the crashdetection sensor is a sensor for predicting a crash to the rear of thevehicle and the control circuit is configured to return the headrest toan initial position by operating the headrest driving mechanism in theopposite direction when a predetermined time passes after the crashdetecting sensor outputs a detection signal.
 22. A headrest controlleras in claim 20, wherein the first sensor includes a plurality ofsensors.
 23. A headrest controller as in claim 20, wherein the firstsensor is a capacitive type sensor.
 24. A headrest controller as inclaim 20, wherein the second sensor includes a plurality of sensors. 25.A headrest controller as in claim 20, wherein first and second sensoreach have a detection output signal, further wherein the control circuitstops the headrest based on the output detection signal of the sensorthat occurs earlier in time.
 26. A headrest device comprising: a frontportion and a back portion; a head position detecting unit including afirst sensor to detect a distance between an object moving towards thefront portion and the front portion, and a second sensor for detectingcontact between the object and the front portion; and a control circuitto alter movement of the front portion based on a detection signal fromthe head position detecting unit.
 27. A headrest device as in claim 26,wherein the first sensor is a plurality of sensors.
 28. A headrestdevice as in claim 26, wherein the first sensor is a capacitive typesensor.
 29. A headrest device as in claim 26, wherein the second sensoris a plurality of sensors.
 30. A headrest device as in claim 26, whereinthe second sensor is a contact type sensor.
 31. A headrest device as inclaim 26, wherein the head position detecting unit is positioned in thefront portion.
 32. A headrest device as in claim 26, wherein the controlcircuit includes a timer.
 33. A headrest device as in claim 32, whereinthe timer is structured and configured to move the front portion after apredetermined amount of time.